The present invention relates to a wick type space heater mainly used for indoor heating and, more particularly, to a space heater capable of completely combusting fuel in a combustion chamber.
Wick type space heaters have prevailed as indoor heating equipment.
The main part of a conventional wick type space heater, e.g., a typical plural cylinder type heater in a kerosene stove has the following construction. The main part comprises a fuel tank, inner and outer flame cylinders concentrically arranged above the fuel tank so as to constitute a combustion chamber therebetween, a narrow annular path for causing the combustion chamber to communicate with the fuel tank, and a cylindrical wick, the lower end portion of which is dipped in kerosene in the fuel tank and the upper end portion of which is inserted in the combustion chamber through the narrow path to soak up kerosene by capillary action. A plurality of vent holes are formed in the inner and outer cylinders to supply air to the combustion chamber. The kerosene vapor evaporated from the upper end of the wick is combusted in the combustion chamber. In addition, by adjusting an exposed portion of the wick in the combustion chamber, the heating power is adjusted.
In such a kerosene stove, the upper end portion of the wick exposed in the combustion chamber is fired by an ignition unit, and air required for combustion is supplied from the plurality of vent holes formed in the inner and outer flame cylinders, thereby accelerating combustion. Heat generated by this combustion heats the exposed upper end portion of the wick in the combustion chamber to increase the evaporation amount of the kerosene. For this reason, the combustion area is gradually increased. When the heat radiated from the upper end portion of the wick is balanced with the heat supplied to the upper end portion thereof, a steady combustion state is achieved.
In such a plural cylinder wick type kerosene stove, however, the following problem is presented. In general, an outer flame cylinder is heated to red-hot, and heat radiated therefrom is used for indoor heating. In order to heat the outer flame cylinder to red-hot, the number of vent holes formed in the outer flame cylinder is about 7 to 10 times that in the inner flame cylinder. The total opening area of the vent holes of the outer flame cylinder is larger than that of the inner flame cylinder to decrease the heat capacity of the outer flame cylinder, thereby heating it to red-hot. During the use of the kerosene stove, the inner flame cylinder is kept at a temperature lower than that of the outer flame cylinder. Since the total opening area of the vent holes of the outer flame cylinder is greatly larger than that of the inner flame cylinder, the amount of air supplied from the vent holes of the outer flame cylinder to the combustion chamber is greater than that of the inner flame cylinder. The fuel vapor evaporated from the upper end portion of the wick flows toward the outer wall surface of the inner flame cylinder due to the influence of air flowing from the outer flame cylinder. The fuel vapor then flows upward in the combustion chamber in the form of a vapor layer. Since the inner flame cylinder is kept at a lower temperature, as described above, part of the fuel vapor rising along the outer surface of the inner flame cylinder is exhausted as a noncombusted fuel vapor, thus generating toxic gases such as CO and THC.